Revert "Fix migration deadlock under Neon pooler"

This reverts commit 30966c6f5e.

internal/database/database.go

@@ -3,7 +3,6 @@ package database
 import (
 	"context"
 	"fmt"
-	"strings"
 	"time"
 
 	"github.com/rs/zerolog/log"
@@ -121,48 +120,6 @@ func Connect(cfg *config.DatabaseConfig, debug bool) (*gorm.DB, error) {
 	return db, nil
 }
 
-// openMigrationDB opens a parallel *gorm.DB pointed at the *direct* (non-pooler)
-// Neon compute endpoint, used exclusively by MigrateWithLock so that
-// pg_advisory_lock (session-scoped) survives across statements.
-//
-// The direct host is derived by stripping the "-pooler" segment from the
-// configured DB_HOST. Example:
-//   pooler  → ep-floral-truth-amttbc5a-pooler.c-5.us-east-1.aws.neon.tech
-//   direct  → ep-floral-truth-amttbc5a.c-5.us-east-1.aws.neon.tech
-//
-// If DB_HOST already lacks the suffix (e.g., a fallback config or a non-Neon
-// PG instance), it's used as-is.
-func openMigrationDB() (*gorm.DB, error) {
-	host := viper.GetString("DB_HOST")
-	port := viper.GetInt("DB_PORT")
-	user := viper.GetString("POSTGRES_USER")
-	pass := viper.GetString("POSTGRES_PASSWORD")
-	name := viper.GetString("POSTGRES_DB")
-	sslmode := viper.GetString("DB_SSLMODE")
-
-	directHost := host
-	if idx := strings.Index(host, "-pooler."); idx > 0 {
-		directHost = host[:idx] + host[idx+len("-pooler"):]
-	}
-
-	dsn := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=%s",
-		directHost, port, user, pass, name, sslmode)
-
-	migrationDB, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
-		Logger: logger.Default.LogMode(logger.Silent),
-	})
-	if err != nil {
-		return nil, err
-	}
-	if sqlDB, _ := migrationDB.DB(); sqlDB != nil {
-		// Single connection is enough — we hold the advisory lock on it.
-		sqlDB.SetMaxOpenConns(1)
-		sqlDB.SetMaxIdleConns(1)
-	}
-	log.Info().Str("direct_host", directHost).Msg("Opened direct DB connection for migration")
-	return migrationDB, nil
-}
-
 // warmUpPool issues N parallel pings so the pool fills with established
 // connections before the first user request lands. Failures are logged but
 // not fatal — the pool will fill on demand under traffic if pre-warm fails.
@@ -243,37 +200,18 @@ func MigrateWithLock() error {
 		return Migrate()
 	}
 
+	sqlDB, err := db.DB()
+	if err != nil {
+		return fmt.Errorf("get underlying sql.DB: %w", err)
+	}
+
 	// Give ourselves up to 5 min to acquire the lock — long enough for a
 	// slow migration on a peer replica, short enough to fail fast if Postgres
 	// is hung.
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
 	defer cancel()
 
-	// CRITICAL: pg_advisory_lock is *session-scoped*. The runtime DB pool
+	conn, err := sqlDB.Conn(ctx)
-	// connects to Neon's pooler endpoint (PgBouncer in transaction mode),
-	// which releases the underlying Postgres session after each transaction —
-	// which would silently release our lock the moment we acquired it.
-	//
-	// So for migrations only, we open a parallel *gorm.DB pointed at the
-	// *direct* compute endpoint (DB_HOST with the "-pooler" segment stripped).
-	// AutoMigrate runs against this direct connection, holding the lock the
-	// whole time. Closed on return.
-	migrationDB, err := openMigrationDB()
-	if err != nil {
-		return fmt.Errorf("open direct migration connection: %w", err)
-	}
-	defer func() {
-		if sqlDB, _ := migrationDB.DB(); sqlDB != nil {
-			_ = sqlDB.Close()
-		}
-	}()
-
-	migSQLDB, err := migrationDB.DB()
-	if err != nil {
-		return fmt.Errorf("get underlying sql.DB: %w", err)
-	}
-
-	conn, err := migSQLDB.Conn(ctx)
 	if err != nil {
 		return fmt.Errorf("acquire dedicated migration connection: %w", err)
 	}
@@ -296,27 +234,15 @@ func MigrateWithLock() error {
 		}
 	}()
 
-	// Run migrations against the *direct* migrationDB while holding the
+	return Migrate()
-	// session-scoped lock on `conn`. Migrate() defaults to the global
-	// `db` (the pooler-backed pool) but the package-level `db` swap during
-	// migration is risky; instead, just call AutoMigrate on migrationDB.
-	return migrate(migrationDB)
 }
 
-// Migrate runs database migrations against the global pool. This is fine
+// Migrate runs database migrations for all models
-// when the global pool is connected via a session (no PgBouncer) — e.g.,
-// in tests with SQLite. In production, MigrateWithLock should be used,
-// which targets a direct Postgres connection.
 func Migrate() error {
-	return migrate(db)
-}
-
-// migrate runs AutoMigrate on the supplied gorm.DB.
-func migrate(target *gorm.DB) error {
 	log.Info().Msg("Running database migrations...")
 
 	// Migrate all models in order (respecting foreign key constraints)
-	err := target.AutoMigrate(
+	err := db.AutoMigrate(
 		// Lookup tables first (no foreign keys)
 		&models.ResidenceType{},
 		&models.TaskCategory{},